The Possible Detection of a Binary Companion to a Type Ibn Supernova Progenitor

Abstract

We present late-time observations of the site of the Type Ibn supernova (SN) 2006jc, acquired with the Hubble Space Telescope Advanced Camera for Surveys. A faint blue source is recovered at the SN position, with brightness {m}_F435W=26.76+/- 0.20, {m}_F555W=26.60+/- 0.23 and {m}_F625W=26.32+/- 0.19 mag, although there is no detection in a contemporaneous narrow-band {{H}}α image. The spectral energy distribution of the late-time source is well-fit by a stellar-like spectrum ({log} {T}_{eff}\gt 3.7 and {log} L/{L}_⊙ \gt 4), subject to only a small degree of reddening—consistent with that estimated for SN 2006jc itself at early-times. The lack of further outbursts after the explosion of SN 2006jc suggests that the precursor outburst originated from the progenitor. The possibility of the source being a compact host cluster is ruled out on the basis of the source’s faintness; however, the possibility that the late-time source may be an unresolved light echo originating in a shell or sphere of pre-SN dust (within a radius 1 {pc}) is also discussed. Irrespective of the nature of the late-time source, these observations rule out a luminous blue variable as a companion to the progenitor of SN 2006jc.